Techniques for objectively evaluating the function of small areas of the human retina will be developed, using visual evoked responses (VER) and electroretinograms (ERG) produced by focal illumination of the retina. These techniques will be applied to patients with different retinal diseases, such as central serous retinopathy, macular degeneration, early diabetic retinopathy, and tapetoretinal degeneration. The results of VER and ERG will be correlated with psychophysical examinations such as kinetic and flicker perimetry, color vision tests, and dark adaptometry; and also with the results of ophthalmoscopic examination, biomicroscopy, stereofundus photography, and fluorescein angiography, for diagnostic and prognostic evaluation.